ICMCTF2001 Session DP-1: Symposium D Poster Session

Wednesday, May 2, 2001 5:00 PM in Room Atlas Foyer

Wednesday Afternoon

Time Period WeP Sessions | Topic D Sessions | Time Periods | Topics | ICMCTF2001 Schedule

DP-1-1 Structural Studies of Carbon Nitrides Thin Films Obtained by Magnetron Sputtering N.A. de Sanchez (Universidad del Valle, Colombia); I. Montero (Instituto de Ciencia de Materiales, Spain); L. Galán (Universidad Autonoma de Madrid, Spain); C. Rincon (Universidad Autonoma de Occidente, Colombia); G. Zambrano, P. Prieto, F. Sequeda (Universidad del Valle, Colombia) CN_x thin films have been deposited by r.f. magnetron sputtering technique using a high-purity 99,99% pyrolytic graphite target at substrate temperatures around 400°C and substrates bias between 0 and -200V. The films were analyzed using Infrared Spectroscopy (IR) that permitted us the determination of the different types of bonding present in the film. X-ray photoelectron spectroscopy (XPS) analysis gives a N/C ratio between 0.23 to 1.3 in the film, depending on the bias. These analysis indicate that the atoms of nitrogen are chemically bonded with carbon in various types as C-N, C=N, CºN in the film
DP-1-2 The Effect of Graphitization by Argon on the Electron Field Emission Properties of the a-C:N Thin Films X.W. Liu, J.W. Hsu, J.H. Lin, S.H. Lai, W.J. Jong, L.T. Chao, H.C. Shih (National Tsing Hua University, Taiwan,ROC) Amorphous carbon nitride thin films were synthesized on silicon as electron emitters by the electron cyclotron resonance chemical vapor deposition (ECR-CVD) system in which a negative dc bias was applied to the substrate holder of graphite and a mixture of Csnb 2Hsnb 2, Nsnb 2 used as precursors. The addition of Ar combined with the application of a negative dc bias can eliminate the dangling bonds in the film determined by Fourier transform infrared (FTIR) spectroscopy, decrease the film thickness measured by field emission scanning electron microscope (FE-SEM), increase the film roughness measured by atomic force microscope (AFM) and raise the graphitic content examined by Raman spectroscopy. An onset emission field of amorphous carbon nitride (a-C:N) with Ar as an extra addition to the precursors can be as low as 6.5 Vµm^-1 compared with 9.5 Vµm^-1 of the film without the addition of Ar.
DP-1-3 The Catalytic Effect of Cu-Ni Alloys on the Formation of One-dimensional Carbon Nanostructured Materials W.J. Jong, S.H. Tsai, X.W. Liu, S.H. Lai, H.Y. Lin, H.C. Shih (National Tsing Hua University, Taiwan,ROC) Carbon nanotubes are known to be synthesized by catalytic chemical vapor deposition (CCVD). Catalysts, e.g., Fe, Ni, Co etc. play an important role in the process of synthesis. Other elements, e.g., Cu, though showing no effect on the growth, have been used to enhance the catalytic effect of Ni by alloying it with Ni. In this study, microwave plasma enhanced chemical vapor deposition (MPECVD) was used to grow one -dimensional carbon nanostructured materials. The result shows that the increase of Cu from 40 at% to 60 at% change the morphology of carbon from tubules to filaments, and the tangled conditions were lessened in this Ni-Cu alloy range. Aligned carbon nanotubes were effectively catalyzed at Cu≤40 at%, and interestingly enough to observe the existence of carbon nanoclusters at Cu≥60 at%. It is not surprising, therefore, that transition metals, e.g., Ni, are typically good catalysts. The catalytic effect of Cu-Ni alloys is prominent at Cu≤60 at%, where d-band is unfilled and favors catalysis of carbon nanotubes. Above 60 at% Cu, the filled d-band is less favorable to the growth of one -dimensional carbon nanostructured materials.
DP-1-4 Characterization of Pulsed Laser Deposited a-C Films by Means of Reflection Energy Loss Spectroscopy G Mondio, F Barreca, AM Mezzasalma, F Neri (University of Messina, Italy); S Trusso (ITS - CNR (Messina), Italy) Amorphous carbon films have been deposited by ablating, with a KrF excimer pulsed laser, a high purity graphite target varying both the laser energy density (up to 15 J/cm²) and the substrate temperature (up to 600°C). Reflection electron energy loss spectra have been carried out in an ultrahigh vacuum surface analysis apparatus, by using a 2.5 keV primary electron beam and a hemispherical sector energy analyser. The loss spectra were processed by removing the elastic peak contribution and the secondary electrons background. The optical functions were deduced using a procedure based on the assumption that surface effects are negligible with respect to the bulk ones ¹. The loss spectra are dominated by the presence of the π and π+σ plasmon resonances, whose energy positions and shapes are significantly affected by the different preparation conditions. In particular it has been possible to determine, on the basis of only REELS data, the sp²/sp³ bonding ratio. On the overall, these results are also relevant for the correlation between the details of the preparation method and the eletronic properties of carbon alloys. ¹ F. Barreca, A.M. Mezzasalma, G. Mondio, F.Neri, S. Trusso, C. Vasi, Phys. Rev. B vol. 62 (2000).
DP-1-5 An Investigation of the Electronic and Structural Properties of Pulsed Laser Deposited a-C Films F Neri, E Fazio, AM Mezzasalma, G Mondio (University of Messina, Italy); S Trusso (ITS - CNR (Messina), Italy); B Fazio (ST Microelectronics (Catania), Italy) The electronic and structural properties of amorphous carbon films have been studied by means of Raman, optical and X-ray photoelectron spectroscopies. The films were deposited, under vacuum, by KrF excimer laser ablation of graphite targets ¹. Both the substrates temperature and the laser fluence were increased up to 900 K and 15 J/cm², respectively. Raman microscopy measurements have been carried out, with a 514.5 nm Ar⁺ laser excitation, in the G and D bands region (800-2000 cm^-1). The results show a substantial independence from the laser fluence (in the investigated range), but a progressive increase of the D band upon increasing the substrate temperature. An apparent slight increase in the deposition rate, upon increasing temperature, seems then to be due to a reduction in the film density, i.e. a progressive graphitization. Analogous systematic modifications were observed in the case of both the optical (reflectivity and transmission) and XPS (evolution of the C 1s photoemission band) measurements. ¹S. Trusso, C. Vasi, F.Neri, Thin Solid Films vol. 355-356, 219 (1999).
DP-1-6 Hydrophobic Fluorinated Carbon Coatings on Silicate Glaze and Aluminum H. Ji (INRS, Univ. Québec, Canada); A. Coté (Hydro-Québec, Canada); D. Koshel, B. Terreault, G. Abel, P. Ducharme, G. Ross (INRS, Univ. Québec, Canada); S. Savoie (Hydro-Québec, Canada) Hydrophobic properties would be desirable for the glazed porcelain insulators and aluminum conductors of high voltage lines. Plasma-enhanced chemical vapour deposition (PECVD) is suited to the deposition of films with good mechanical properties and adherence. Fluorinated carbon was deposited on silicate glaze and aluminum using our PECVD system, with an Ar/C₂H₂/C₃F₈ chemistry selected for its low cost and low toxicity. A wide range of process parameters was explored: from low (~0.01 Torr) to intermediate (~0.04 Torr) to high pressure (<1 Torr), and self-bias from -50 to -1000 V. Measurements including film thickness, contact angle (advancing/receding) for wetting properties, X-ray photoelectron spectroscopy (XPS) for determining the film composition and bonding states, optical microscopy, atomic force microscopy (AFM), nano-indentation, and scratch test were performed. Adherence of a covalently bonded coating on an ionic or metallic substrate is a basic problem that has been addressed by the use of intermediate layers consisting respectively of silicate/a-Si/a-C/a-CF_x and Al/Al₄C₃/a-C/a-CF_x, with film thickness ranging from hundreds of nanometers to a few microns. The fluorine content was <30 at. %, with clearly identified CF_n (n=1~3) groups as well as C-C cross-linking bonds. Advancing contact angle as large as 130° has been obtained. The mechanical properties varied from DLC-like to polymer-like, with the medium pressure coatings presenting an ideal combination of hardness and hydrophobia. High pressure coatings have a rough columnar morphology while the low and intermediate pressure ones are smooth.
DP-1-7 Synthesis of Multi-Layered Diamond Film and Evaluation of Its Mechanical Properties S. Takeuchi, S. Oda, M. Murakawa (Nippon Institute of Technology, Japan) Diamond has high anti-abrasion property because of its hardness. However, the brittleness of the material sometimes causes cracking when it is used, for example, as the material for cutting tools. The structure of diamond films synthesized by CVD method is polycrystalline with columnar grown crystals in general. Then, this causes a problem that this structure easily allows the propagation of cracking yielded on the surface of the film, resulting in decrease of the toughness of the film in total. This paper deals with the synthesis of multi-layered diamond film, by a hot filament CVD method, which can prevent continuous growing of the columnar crystal by forming the interlayer of secondary nucleus between the growths through the application of intermittent bias current to the substrate on which the columnar crystal grows. Mechanical properties of prepared film were evaluated by bending and anti-abrasion tests which resulted in showing the improvement of bending strength, for example, as much as 30 %.
DP-1-8 Formation of Nanostructures by Heat-Treatment of Cobalt-Containing Amorphous Carbon Films Y.J Li, S.P. Lau, B.K. Tay, Z Sun, G.Y. Chen, X.Z. Ding, J.S. Chen (Nanyang Technological University, Singapore) Obalt-containing amorphous carbon films have been deposited on silicon substrates by filtered cathodic vacuum arc technique using cobalt-containing graphite targets with increasing cobalt atomic percepts. After heat-treatments at 550°C in nitrogen, the nanostructures of the heat-treated carbon films, which were characterized by Raman spectroscopy, atomic force microscopy and high-resolution scanning electron microscopy, were significantly modified when the concentration of cobalt over 10 %. With introducing a mixture of acetylene and nitrogen gases, some carbon nanofibers were formed after heat-treating the cobalt-containing films at 550°C. The density and the diameter of nanofibers controlled by the atomic percepts of cobalt in the films and the heat-treated temperature were investigated. This provides an alternative method to control the growth of carbon nanofibers and nanostructrues for field emission applications. .
DP-1-9 Electron Emission From Low Temperature Synthesized Carbon Nanotubes G.Y. Chen, Z Sun, Y.J Li, J.S. Chen, B.K. Tay (Nanyang Technological University, Singapore) The excellent electron field emission properties of carbon nanotube films are promising as a cold cathode electron source. Carbon nanotubes are deposited on sputtered nickel film by hot filament decomposition of hydrocarbon precursor (C₂H₂/H₂) at relatively low substrate temperatures (350^°C ~ 500^°C). Randomly oriented nanotubes of varying diameters (10nm ~ 100nm) with lengths up to tens of microns were produced. The films were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscope (TEM), Micro-Raman spectroscopy and X-Ray Diffraction (XRD). The growth aspects of carbon nanotubes at low temperatures and its electron field emission properties are investigated. The carbon nanotube film exhibit good electron emission properties, e.g. low threshold emission field (~ 2 V/mm) and high emission current density (~ 1 mA/cm2 at 10 V/mm).
DP-1-10 Microstructure Analysis of Nano-Composite Diamond-Like Carbon Films Synthesized by Unbalanced Magnetron Sputtering D.Y. Wang, C-H. C. Chang (National Chung Hsing University, Taiwan, ROC) Diamond-like carbon (DLC) films posses significant advantages in cutting and forming of non-ferrous materials. Diamond-l ike carbon film is characterized by its extreme hardness (1000-3000kg.mm2) and low friction coefficient (0.01-0.28 against vari ous metals). However, further improvement in fracture toughness and interface adhesion is required for certain high demanding applications such as deep drawing and semiconductor molding. In this study, metal-doped DLC films were synthesized using unbal anced magnetron sputtering (UBMS) process with a combination of graphite and metal targets. The result is a nano-composite DLC film with interlaced metal interlayers. The cathode currents and rotation speed of substrate holder control the thickness of each interlayer. A pulsed d.c. power supply, with 20-100 kHz variable-frequency was applied to the substrates to control the s ubstrate arcing and radical excitation during the DLC formation. The influences of deposition parameters on film qualities wer e investigated. Microstructure of the nano-composite DLC film was investigated by using cross-section TEM/SAD, x-ray spectroscopy and XPS. The correlation between the microstructure and the tribological properties of DLC will be analyzed.
DP-1-11 Surface Enhancement of Diamond-Like Carbon Films by Metal Plasma Ion Implantation Process C.L. Chang, D.Y. Wang (National Chung Hsing University, Taiwan, ROC) Diamond-like carbon (DLC) films posses superior mechanical, optical, thermal, and electrical properties for advanced eng ineering applications. However, the excessive residual stress of DLC induces fracture failure and severe interfacing difficult y to metallic substrates. In this study enhancement of surface properties of DLC such as surface density, sp3/sp2 bond conversion, and degree of crystallinity at the near-surface regime was conducted with an energetic ion implantation. The post-treatment of the as-deposited DLC film was carried out with metal plasma ion implantation (MPII) process. MPII is a p lasma-based ion implantation process based on an accelerated (10-80 keV) vacuum arc metal plasma source with multiple charge st ates. Carbon and/or metal ions with flux more than 1*10 17 ions/cm2 was implanted into DLC films. The formation mechanism of DLC, carbides, and carbo-nitrides under the influence of MPII were investigated. The surface study will be followed by series of microstuctural and tribological analyse
DP-1-12 Discharge Behavior of Arc Ion Plating on Various Kinds of Graphite Cathodes Y. Azuma (Keio Uniyersity, Japan); A. Kimura, T. Suzuki (Keio University, Japan) When diamond-like carbon (DLC) films are synthesized by the arc ion plating (AIP) method using carbon cathodes, the emission of macroparticles from cathodes is obstacles to obtain uniform and smooth surface. The anchoring of the cathode spots on carbon cathodes causes more numbers of macroparticles than that of metallic cathodes. In order to improve discharge behavior of carbon cathodes, we sintered carbon cathodes with sintering aids such as Ti and B₄C by the hot-pressing method. Pyroid and other commercially available graphite were also used for the experiments. Ti, B₄C and C powders were mixed and sintered in Ar atmosphere with press of 15 MPa at 2200 °C changing Ti ratio in order to decrease electrical resistivity. Using these cathodes, DLC films (a-C, a-C:Ti) were synthesized on WC-Co and Si substrates by the AIP method. It was found that the discharge behavior was improved by controlling microstructure of graphite cathodes, such as the number and size of pore space, grain size and Ti ratio.
DP-1-13 Determination of the Elastic Properties of Cubic and Hexagonal Boron Nitride Films by Surface Acoustic Wave Spectroscopy G. Lehmann, P. Hess (University of Heidelberg, Germany); P. Scheible, A. Lunk (University of Stuttgart, Germany); S. Weißmantel, G. Reisse (Hochschule für Technik und Wirtschaft Mittweida, Germany); R. Freudenstein, W. Kulisch (University of Kassel, Germany) Surface acoustic wave spectroscopy (SAWS) was used to determine the elastic properties (e.g. the Young's modulus) and the density of cubic boron nitride thin films, which have been deposited by a number of different methods, namely ion-assisted pulsed laser deposition, hollow cathode arc evaporation, and bias-assisted inductively coupled plasma CVD. Since c-BN deposition reveals a complex nucleation behaviour which includes a textured h-BN layer, and since in addition usually sp² bonded BN interlayers are used which are necessary to assure the adhesion of the c-BN films, various h-BN, t-BN and amorphous BN films have been investigated also in order to be able to evaluate the properties of the c-BN toplayer. For example, for h-BN layers with the c-axis normal to the substrate surface a Young´s modulus of 92 GPa has been measured. For c-BN films, on the other hand, typical values of the Young's modulus are in the range from 420 to 550 GPa, those of the density in the order of 2.9 to 3.2 g/cm³. Both are considerably lower than the values of bulk HPHT c-BN (800 GPa and 3.47 g/cm³, respectively) but are in resonable agreement with data obtained by other techniques. A possible reason for this deviations from bulk properties is the nanocrystalline nature of the c-BN films. Finally, the differences of the moduli and densities found for various samples from the different techniques are discussed in terms of other film properties, especially the c-BN content.
DP-1-14 A Novel Method of Fabricating ZnO/Diamond/Si Multilayers for Surface Acoustic Wave(SAW) Device Application W.C. Shin, S.H. Seo, J.S. Park (Hanyang University, South Korea) Materials with high phase velocity are required to achieve high frequency surface acoustic wave(SAW) devices, and diamond is the most appealing material for creating new materials. ZnO/diamond/Si multilayers have exhibited phase velocities as large as 10km/s, which enables high frequency (>2GHz) SAW devices without requiring submicron process technologies. However, there still exist pratical difficulties in implementing the diamond-based SAW devices; As-deposited diamond films exhibit a high surface roughness, typically greater than several hundreds to thousands angstroms. In addition, during the dicing process few cracks often occur due to its high hardness. These have caused the degradation of device characteristics, such as distortion of frequency responses and formation of open and/or short circuits between interdigital transducer(IDT) electrodes, as well as the decrease of device fabrication yield. In this study, we propose a novel method to avoid the problem in fabricating diamond-based SAW devices. Main processes performed are as follows; The 1µm-thick SiO₂film is deposited on Si wafer(bottom) and patterned by photolithography. To form a trench of 10µmin depth the Si is chemically etched by employing the SiO₂layer as a mask. Polycrystalline diamond films are deposited by a microwave plasma CVD with the nominal conditions of 40 Torr pressure, 1.0% CH₄/H₂ratio, 750°C temperature, and 90V bias enhancement. After removing the SiO₂layers, indirect bonding of Si wafer(top) is performed at temperatures below 400°C. Finally, the bottom Si is then polished until the deposited diamond layer is exposed. Raman and FE-SEM observations show that high quality polycrystalline diamond films can be selectively grown exclusively on the trenched Si regions. AFM results show that the surface roughness of the exposed diamond film is at most 10nm. Future experimental details on finding the optimal conditions for wafer bonding and polishing will be presented. ZnO/diamond/Si multiplayer SAW devices fabricated by using the proposed method show the reproducible frequency response characteristics at high frequency ranges of 1~3GHz.
DP-1-15 Field Emission of Nanostructured Amorphous SiCN Films Deposited by Reactive Magnetron Sputtering of SiC in CH₄/N₂ Atmosphere H.Y. Lin (Chung-Cheng Institute of Technology, Taiwan,ROC); Y.C. Chen, L.G. Hwa (Fu-Jen University, Taiwan, ROC); K.H. Chen (Academia Sinica, Taiwan, ROC); L.C. Chen (National Taiwan University, Taiwan, ROC) Nanostructured and amorphous silicon carbon nitride (SiCN) films have been deposited by magnetron sputtering of silicon carbide under reactive gas environment. Gas mixtures containing methane and nitrogen with various ratios were used for deposition. Auger, XPS, FTIR and micro-Raman were employed to characterize the composition and bonding structures, while SEM and TEM were used to investigate the microstructures of the SiCN films. As the methane to nitrogen ratio was increased, the SiCN films changed from mirror-like smooth films to column-like and ridge-like C-rich SiCN nanostructures. Micro-Raman studies also showed some blueshift and narrowing of the G band at higher methane concentrations, suggesting an increase of the short-range order graphite-like phase in the nanostructured films. The sharper geometric features of the nanostructured SiCN films and possibly the higher conductivity of the films led to an enhancement in field emission properties. A low turn-on field (< 10 V/µm) and high emission current (> 0.2mA/cm²) as well as good temporal emission stability have been achieved for the nanostructured SiCN films.
DP-1-16 Development of Porous Diamond Tubes V. Baranauskas, A.C. Peterlevitz, H.J. Ceragioli, A.L. Souto (Universidade Estadual de Campinas, Brazil); S.F. Durrant (Feec, Unicamp, Brazil) Diamond tubes are of interest for special applications such as waveguides, and in X-ray imaging, field electron emission devices, drilling tools, molecular filters and so on. In this work we discuss the fabrication of diamond tubes using a hot-filament chemical vapor deposition (CVD) system fed ethanol highly diluted in hydrogen and argon. Tungsten wires were used as substrates. Owing to the convex surface of the substrate, there is reduced competition for space, and therefore a tendency towards greater grain sizes in the evolution of columnar growth. The presence of argon, however, minimizes the deposition of hydrogenated material in the intergranular spacing, with the creation of radial pores parting from the tungsten surface towards the outer surface of the diamond tube. Such radial pores are of great interest in the use of these diamond tubes for molecular separation of gases and liquids. Data obtained by scanning electron microscopy (SEM) and micro-Raman spectroscopy of the surface and of cross-sections of these tubes are presented and discussed.
DP-1-17 Structural Properties of Diamond and Diamond-Like Carbon Grown on Stainless-Steel Substrates V. Baranauskas, A.C. Peterlevitz, H.J. Ceragioli, A.L. Souto (Universidade Estadual de Campinas, Brazil); S.F. Durrant (Feec, Unicamp, Brazil) The deposition of high quality layers of diamond on steel is very attractive for a wide number of possible applications, ranging from cutting tools to protective coatings for car bodies. Diamond growth on steel, however, requires a heterogeneous nucleation step and also the formation of an interface layer between the substrate and the diamond. Nucleation times may be very long and nuclei densities may also be very low, which may compromise the film quality for particular applications. Moreover, the properties of the interface layer need to be compatible with good adhesion between the substrate and the film. The deposition parameters must be adjusted to produce a carbide interface layer, distinctly different from the graphite lamellar structure, which produces poor mechanical adhesion between the diamond and the steel. In this work, we discuss the feasibility of diamond seeding and oil coating to increase diamond and diamond-like carbon nucleation on, and improve adhesion to, stainless steel. The resulting nuclei and films were monitored using Raman spectroscopy and characterized by optical, scanning electron and atomic force microscopies. .
DP-1-18 Growth of Diamond and Diamond-Like Carbon on Natural Pyrolized Fibers V. Baranauskas, A.C. Peterlevitz, H.J. Ceragioli, A.L. Souto, S.F. Durrant (Universidade Estadual de Campinas, Brazil) Diamond and diamond-like carbon (DLC) coatings of natural pyrolized fibers may be used in the future manufacture of batteries or to produce new types of molecular filters. In this work, we demonstrate the feasibility of the chemical vapor deposition (CVD) of diamond-like materials onto natural fibers, originated from high-density wood or bamboo. In addition, we demonstrate the coating of such structures with high quality diamond following the seeding of these substrates with diamond grains prior to CVD. A hot-filament CVD system fed with ethanol, was used. Such a process is shown to produce a highly porous structure or a very rough film formed by embedding the natural fibers with CVD diamond and DLC grains. Critical discussion of the results of surface and cross-section analyses of samples by scanning electron microscopy and micro-Raman spectroscopy is given.
DP-1-19 Investigation of Nitrogen Bonding in Amorphous Carbon Nitride W.J. Gammon, B. C. Holloway, A.C. Reilly (College of William and Mary); O. Kraft (Max-Planck-Institut für Metallforschung, Germany) Previous work has shown that the N(1s) spectra of highly elastic amorphous carbon nitride (a-CN_x) can be resolved into two peaks positioned at ~ 398.5 and 401 eV. ¹ Furthermore, the exact location and intensity of the two peaks can be directly correlated to the mechanical properties of the film. ² However, the actual bonding configurations responsible for the chemically shifted peaks are poorly understood. One method to interpret nitrogen bonding in a-CN_x x-ray photoelectron spectroscopy (XPS) spectra is by comparing the location of chemically shifted peaks to spectral features from reference materials that have been reported in the literature. However this procedure is complicated by the fact that published reference spectra absolute energy values often vary. In this work, a-CN_x films were deposited on a heated Si(001) substrate by DC magnetron sputtering. Nanoindentation was used to confirm that the films were highly elastic and mechanically hard. XPS was used to elucidate nitrogen bonding in a-CN_x by directly comparing the carbon nitride N(1s) spectra with N(1s) peak positions from a variety of organic compounds characterized in the same system. These compounds are representative of particular N bonding environments thought to be found in carbon nitride. To eliminate any discrepancy in absolute peak position that may be introduced by sample charging, XPS measurements in this study are all referenced to a common absolute binding energy. In addition, the XPS results are correlated with other high-level characterization techniques and computational models of carbon/nitrogen structures ¹ ¹ B.C. Holloway, O.Kraft, D.K.Shuh, M.A. Kelley, W.D. Nix, P. Pianetta, and S. Hagström, Appl. Phys. Lett., 74, 3290 (1999). ² N. Hellgren, M.P. Johansson, E. Broitman, L. Hultman, and J. Sundren, Phys. Rev. B, 59, 5162 (1999).
DP-1-20 Elastic Properties of Boron Nitride Films T. Wittkowski, J. Jorzick, K. Jung, B. Hillebrands (Universität Kaiserslautern und Schwerpunkt Materialwissenschaften, Germany) Hexagonal boron nitride (h-BN) films, thin h-BN/c-BN films and thick c-BN films were investigated using the Brillouin light scattering (BLS) technique. The dispersion of the phase velocity of surface modes for film thicknesses smaller than the phonon wavelength (0.3 - 1 µm) bears in general sufficient information to deduce several independent components of the elastic tensor. In the case of thick c-BN films a quasi-longitudinal bulk mode is used additionally to fully determine the elastic tensor. From the so-called effective elastic constants the elastic moduli are deduced. The main result in case of the h-BN films is the pronounced elastic anisotropy up to c₁₁/c₃₃ = 0.1 which is mainly caused by the single crystal anisotropy in a strongly textured nanocrystalline material. Layered h-BN/c-BN films lead to an oscillatory behaviour of the lowest surface mode with increasing wavevector. For large wavevectors the discrete modes are guided in the compliant h-BN layer. In c-BN films a correlation between the linewidth of the Rayleigh mode and the grain size near the film surface is observed. The damping is due to the internal boundaries, hence the morphology near the surface can be inferred from the linewidth. The investigations on a thick c-BN film yield a reduced bulk modulus of the film material compared with the single crystal. In addition, a moderate elastic anisotropy is present mainly due to the structured film growth. Work supported by the Deutsche Forschungsgemeinschaft.
DP-1-21 Determination of Biaxial Modulus of Diamond Films Deposited on Ti90Al6V4 Foil Q.H. Fan, J. Gracio, E. Pereira (University of Aveiro, Portugal); C.J. Tavares, V. Teixeira (Universidade do Minho, Portugal) A new approach for determining biaxial modulus of chemical-vapor-deposited diamond films is presented with an example of diamond coating on Ti90Al6V4 thin foil of 15x5mm in dimension. The biaxial moduli of the film and the substrate are calculated from a combination of bimetal theory and plate bending theory. To realize a valid calculation, residual stresses in the film and curvature radius of the sample need to be known independently. Raman spectroscopy was employed to evaluate residual stress and a laser displacement meter was used to measure the sample deflection. Raman spectra of the as-grown diamond showed that the film was under a compressive stress of ~6.8 GPa, while the corresponding free-standing film obtained by etching off the metal substrate was nearly stress free. The sample surface was almost flat before the diamond coating, while the it curved with the film on the convex side after the diamond deposition. The calculated biaxial modulus for the diamond film was about 950 GPa. This implied that the diamond film possessed a relatively high quality, which was confirmed by its Raman spectra. .
DP-1-22 B-C-N Coatings Prepared by Microwave Chemical Vapor Deposition A.V. Stanishevsky, H. Li (University of Maryland); A. Badzian, T. Badzian, W. Drawl (The Pennsylvania State University); L.Yu. Khriachtchev (University of Helsinki, Finland); E. McDaniel (Microelectronics Research Laboratory) Ternary B-C-N amorphous and crystalline coatings were deposited by microwave chemical vapor deposition using a mix of NH₃, CH₄, B₂H₆, and H₂ gases at substrate temperature in the range of 800 - 1200 °C and the gas pressure of 80 Torr. The coatings were analyzed using SEM, high-resolution TEM, scanning Auger microscopy, SIMS, Fourier-transform infrared and Raman spectroscopies. We studied the influence of the deposition conditions (partial gas pressures, substrate temperature, substrate material) on the coating structure, chemical composition, and surface morphology. Specific attention was paid to the investigation of the interface region between the coating and structure. Both amorphous and polycrystalline coatings were deposited. Amorphous coatings are usually formed at lower substrate temperatures and they have non-uniform density across the coating thickness. Nanocrystalline inclusions of boron carbide, boron nitride, and diamond were observed in amorphous B-C-N compounds. Polycrystalline coatings are generally represented by both diamond and boron nitride phases. In one case, a polycrystalline coating with the composition of B_0.28C_0.14N_0.56 was fabricated. A detailed discussion of the experimental data is provided. .
DP-1-23 Synthesis of Diamond-Like Carbon Films by Pulsed Plasma Technology Y.C. Hsieh, D.Y. Wang (National Chung Hsing University, Taiwan, ROC) Diamond-like carbon (DLC) films posses superior mechanical, optical, thermal, and electrical properties for advanced eng ineering applications. DLC films have been synthesized by various vacuum deposition processes such as PECVD, laser ablation, magnetron sputtering, and cathodic arc evaporation. Due to the dielectric property of DLC, a RF power supply in conjunction with a matching network connected to the substrate holder is necessary to maintain the discharge stability. However, the RF powered deposition system is prohibitive for coating of large areas due to the poor plasma uniformity, electromagnetic interference, and equipment costs. In this study, amid-frequency (2-100 kHz), pulsed DC power supply was applied to the substrate holder. In addition to the arc suppression at substrates, the dissociation of hydrocarbon precursors was effectively enhanced by the pulsed plasma configuration. The influence of frequency and pulse shape of the power waveform upon microstructure and tribological properties of DLC films will be discussed.
DP-1-24 Analysis for Hydrogen in BCN Films by Nuclear Reaction H. Yasui, Y. Hirose, T. Sasaki (Kanazawa University, Japan); K. Awazu (Industrial Research Institute of Ishikawa, Japan); H. Naramoto (Japan Atomic Energy Research Institute, Japan) Hydrogen is a very common contaminant in carbon films. It can strongly influences on mechanical, physical and chemical properties of the films. The analysis of hydrogen is therefore a crucial problem to prepare the films with the reproducible property. Ion beam techniques using nuclear reactions are established methods for the quantitative determination of hydrogen concentration. A spectrometer has been constructed for the determination of hydrogen concentrations by detecting 4.43MeV $B&C(B-rays from the resonant nuclear reactions 1H(15N,$B&A&C(B)12C at the 6.385MeV. The detailed hydrogen analysis was made mainly on BCN(Boron Carbonitride) thin films. The BCN films were prepared by ion beam assisted deposition, in which boron and carbon were deposited by electron beam heating of B4C solid and nitrogen was supplied by implantation simultaneously. The mechanical properties of BCN films were evaluated using an ultra-micro-hardness tester. The hardness increase obtained can be correlated with the hydrogen concentration.
DP-1-25 Hardness and Elastic Modulus off Carbon-Germanium Alloys J. Vilcarromero, F.C. Marques (UNICAMP, Brazil) The carbon atom ability to make bonds with different hybridization allows the preparation of a large variety of materials with different structure such diamond, graphite, polymeric films, and nanostructures. The investigation of the carbon properties in different network helps us to understand its properties in addition to the development of new materials. In this work we investigated the properties of carbon-germanium alloys prepared by the sputtering technique, which allowed the preparation of thin films in the whole composition range, i.e. from 0% up to 100% carbon content range, using the same deposition conditions and varying the target composition. The elastic modulus, thermal expansion coefficient, stress, and nanohardnes of these films were investigated. It was observed that the stress of the alloys decreases in relation to the pure films, a-Ge:H and a-C:H, indicating the degradation of the structure of the alloys. Contrarily to what was expected, the hardness, as well as the elastic modulus, of the alloys with small concentration of carbon is smaller than that of pure germanium films. These properties are analyzed in terms of the structural properties of the films determined by infrared spectroscopy.
DP-1-26 In Situ Measurement of Residual Stress During Deposition of cBN Film Using Unbalanced Magnetron Sputtering H.S. Kim (Korea Institute of Science and Technology (KIST), Korea); I.H. Choi (Korea University, Korea); Y.-J. Baik (Korea Institute of Science and Technology (KIST), Korea) We designed an in situ method for measuring a residual stress to investigate a stress evolution during a cubic boron nitride (cBN) growth. Thin (100 ± 10 µm thickness) Si strip of 4 X 45 mm was used as a substrate, which was bended by compressive stress of deposited film during deposition. The curvature of the substrates during deposition was recorded using CCD camera, which was placed in front of Si strip through the tempered glass window. From the CCD camera image, the curvature of the substrates deposited with BN films was calculated. We used hBN as target material, which was sputtered in plasma with argon - 10% nitrogen mixed gas. In order to induce a substrate bias voltage, we connected a DC power supply to the substrate. The bias voltage was fixed at -120 V. For cBN growth, the assistance of ion bombardment is required, so total momentum is considered as an important parameter. In this study, we controlled the total momentum per arriving atom by change of target power and target-substrate distance, and observed the change of total stress of cBN films. The residual stresses decreased with increasing target power and with decreasing target-substrate distance. It was confirmed that the total momentum per arriving atom is very important factor for cBN growth and the residual stress is controlled by change of cBN growth rate.
DP-1-27 Observation of cBN films, Grown by Unbalanced Magnetron Sputtering, by High-Resolution Transmission Electron Microscopy H.S. Kim (Korea Institute of Science and Technology (KIST), Korea); I.H. Choi (Korea University, Korea); Y.-J. Baik (Korea Institute of Science and Technology (KIST), Korea) Orientation relation between cubic boron nitride (cBN) and underlying turbostratic BN (tBN) layer was investigated using high-resolution transmission electron microscopy. We used hBN as target material, which was sputtered in plasma with argon - 10% nitrogen mixed gas. In order to induce a substrate bias voltage, we connected a DC power supply to the substrate. The bias voltage was varied from - 85 V to -120 V. The microstructure of cBN films was investigated using 300 keV (HITACHI H-9000 NAR) high-resolution microscopy. In this study, it was generally observed that the cBN (111) planes were grown continuing tBN (0002) planes with parallel lattice fringes. However, some of the interfaces had a different orientation relation between cBN and tBN layer. The cBN grains were grown with columnar structure from tBN to the surface. Orientation relation between cBN and tBN layer was discussed.
DP-1-28 Multiplayer DLC Film Being Endurable at High Contact Pressure J.K. Kim, J.J. Rha, K.H. Lee, S.R. Lee (Korea Institute of Machinery & Materials, Korea) Hydrogenated DLC and Si incorporated DLC films were coated alternately using end hall ion gun on AISI M2 steel that was cleaned by Ar sputtering and followed by coating Si and Silicon Carbide as glue layer. Precursors were bengen and dilute silane gas for H-DLC and Si-DLC films respectively. Thickness of DLC films and coating sequences were changed as experimental parameters. Multiplayer DLC films were designed for increasing total thickness as reducing residual stress and having low coefficient of friction as much as 0.02 during 100,000 cycles at 2 GPa of maximum Hertzian pressure. Coefficient of friction were monitored by ball-on-disc type tribometer under the 5N of applied load and 0.24 m/sec of velocity. Ruby ball was used as mating material and its diameter was 3mm. At the 5% of relative humidity environment all specimen showed low coefficient of fiction as much as 0.02 except of the specimen that had highly Si incorporated DLC films. However at 80% R.H. coefficient of friction were risen to 0.1. In this experiment hydrogenated DLC films showed low coefficient of friction and wear rates rather than Si incorporated DLC films.
DP-1-29 Stability of Sub-Atom Carbon Films on the Surface of Metals to the Low-energy Gas Ions Bombardment A.L. Suvorov (SSC RF Institute for Theoretical and Experimental Physics, Russia) he developed original experimental technique to analyze parameters of low-frequency oscillations of field electron current for the metal-film systems ¹ has been used in the present work to measure sputtering yields of Y carbon films (degree of covering θ = 1…5) on Ti, Fe, Nb, Ta ? U. The method was used in a higher accuracy when a substantial difference of the values of the work function of the film (fi_f) and the substrate (fi_sub); it was necessary to suit the conditions when fi_f was higher than substrate fi_sub. The directly measured values were amplitudes of abnormal fluctuations of the field electron current δI_fe, caused by bombardment of the film by single ions. Calculation of the sputtering yields Y was carried out with the help of the analytical examination of the expression of the developed model. The films were applied by evaporation of the carbon target by the pulse laser in vacuum. The thickness of the film (degree of covering θ) was controlled due to variations of the field electron emission current during their application. Sputtering yields Y of carbon films by H ⁺ and ?? ⁺ with the energies ?_i. in the range 2,0 ¸10 kiloelectron Volts were measured. Energy functions of Y for the fixed values of θ were obtained for the ions of each type; besides, for some fixed values of the energy of ions ?_i, for each type of ions functions Y to θ were obtained. The measured values Y for all cases were lower than those for bulk carbon. Finally, application of an other original method combining the field ion microscopy and precise measurement of the light characteristics of local areas of field ion images ², has allowed to analyze energy thresholds ?_th of the beginning of sputtering of carbon films on the metal surface. Substantial variation of the values of Eth for θ » 1 and θ ≥ 2 was revealed. ¹ ¹ A.L.Suvorov, E.P.Sheshin, D.E.Dolin, G.G.Kuzyakhmetov. Field electron current noise of metal-film emitters. Appl.Surf.Sci.,1994, v.76/77, p.26. ² M.I.Guseva, A.L.Suvorov, S.N.Korshunov, N.E.Lazarev. Sputtering of beryllium, tungsten, tungsten oxide and mixed W-C layers by deuterium ions in the near-threshold energy range. J.Nucl.Mat., 1999, v.266-269, p.222.
DP-1-31 A Study of the Oxidation of Combustion-Deposited Diamond Films by Raman, FTIR Spectroscopy and TGA L.M. Apátiga (UNAM, Mexico); D. Mendoza-Anaya (Instituto Nacional de Investigaciones Nucleares, Mexico); V.M. Castaño (UNAM, Mexico) The oxidation of polycrystalline diamond films at temperatures ranging from 400 to 1000 ?C in open an atmosphere was studied by Raman, Fourier Transform Infrared (FTIR) spectroscopy and Thermogravimetric Analysis (TGA). The films were synthesized by the combustion flame technique using an oxy-acetylene gas mixture. The Raman spectrum from as-deposited diamond films showed a sharp band at 1332 cm-1 characteristic of the sp3 diamond structure, with a very weak and broad features in the background and near 1560 cm-1, indicating that there exists a low amount of non-diamond or graphite content on diamond surfaces. This small quantity of graphitic material was removed after the heat treatments as a result of the strong reaction with the oxygen on the diamond surfaces. Moreover, it was found no experimental evidence for graphitization during the oxidation process, as far as Raman spectroscopy was able to detect. On the other hand, the chemisorbed species formed during the synthesis process and after the heat treatments were easily observable by infrared spectroscopy, their role on the oxidation process at different temperatures is discussed, as well. A typical TGA curve for a sample heated up to 1000 ?C showed an appreciable weight loss due to oxidation that starts at 600 ?C and progresses rapidly to 1000 ?C. Kinetic data were collected to determine the activation energy of the diamond films oxidation.
DP-1-32 Relaxation of Internal Stress of cBN Film by Means of Al Addition S.K Kurooka, T.I. Ikeda (Japan Fine Ceramics Center, Japan); N.I. Iwamoto (Ion Engineering Research Institute Corporation, Japan); A.T Tanaka (Aist, Miti, Japan) Thin cBN film is one of the most attractive materials, because its characteristics such as hardness, wear-resistance and oxidization resistance are very outstanding. To date, a number of deposition technique has been used to synthesize cBN films, so cBN thin films were obtained successfully under optimal deposition conditions. However, the films usually showed partial peeling from substrates after deposition due to the large compressive stress. For the relaxation of them, the various techniques were tried, such as the formation of graded layer and different materials layer between the cBN film and the substrate. On the other hand, very few studies have been reported with respect to the addition of the third elements to cBN films. In this study we tried to relax its internal stress by means of the addition of Al to cBN films. The cBN films added Al have been prepared by dual-ion beam sputtering method. The chemical structure and compositions of the films were investigated by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, respectively. Also nanoindentation method was carried out to measure the film hardness. Internal stress was estimated by bending beam method. Moreover, oxidization resistance of the cBN added Al films was investigated in air under various conditions such as temperature and holding time. With the increase in Al addition, the contents of cubic phase in BN-Al films were reduced, and the structure of films changed to hexagonal phase over 3.5% contents of Al, while the internal stress of 6GPa and the hardness value of 60GPa were reduced to 2GPa and 25GPa, respectively. The oxidization resistance of the cBN film added 1.8 at%-Al was improved drastically compared with that of a pure-cBN film. So, we conclude the addition to Al to cBN film is very useful technique to prevent from peeling and control the high hardness and the internal stress, moreover improve the oxidization resistance.
DP-1-33 Ion Beam Nucleation of Diamond on Si - a Systematic Study F.Y. Meng, Quan Li (City University of Hong Kong, China); Y. Lifshitz (Soreq Nuclear Research Center, Israel); I. Bello, S.T. Lee (City University of Hong Kong, China) A systematic study of diamond nucleation on Si by direct ion-beam is performed to understand the ion-induced nucleation mechanism and different experimental parameters in affecting diamond nucleation. Ion bombardment using an ion source consisting of a mixture of hydrocarbon/argon/hydrogen ions is capable of nucleating diamond over a large range of experimental conditions at a low (10^-4 Torr) pressure. Other than the deposition temperature and ion energy effects, different hydrocarbon species (CH₄ and C₂H₂) were used to compare the hydrocarbon effect. Moreover, the gas concentration effect was also investigated by varying the hydrocarbon concentration in the reactive gas mixtures. SEM images taken from the samples exposed to ion beams with doses of 10¹⁸ - 10¹⁹ cm^-2 at energies from 100 to 300 eV showed uneven, granular morphology, with a typical grain size of about 200 nm. Raman spectra indicated graphitic structures with no observable diamond peaks at 1330 cm^-1. However, nano-crystalline diamond in the film was detected by a small peak at a Raman shift of approximately 1080 cm^-1. Cross-sectional high-resolution transmission microscopy (HRTEM) indicated predominant amorphous carbon structure with small diamond crystallites.The diamond crystallites were approximately 2 to 10 nm in diameter. They were either embedded in the amorphous carbon matrix or attached to different sites of silicon.
DP-1-34 Development of High Performance Diamond Coated Drills for Cutting Silicon Aluminum H. Hanyu (Osg Corporation, Japan); S. Kamiya (Tohoku University, Japan); Y. Murakami, H. Odagi (Osg Corporation, Japan) Recently, the automobile industry has had an increasing need for machined aluminum. Due to this, there has arisen a corresponding need for tools to perform efficient and effective aluminum processing. In machining aluminum alloy which contains a large amount of silicon , we need highly wear-resistant cutting tools such as diamond coated ones because of silicon particles in the matrix of aluminum, which quickly wear the tools. However, diamond coatings on cutting edges actually debond off easily. In order to improve the adhesion of diamond coatings on cutting edges, we tried to optimize the construction of coated drills by changing the shape of cutting edges, coating thickness, and structure of coatings We prepared 4 different shapes of drills which have the spiral angles of 12o, 20o, 30o and 38o, respectively. The drills with 20o spiral angles showed the best performance including durability. The two thickness of coatings, 25 and 40 micron, were also compared. The maximum durability was found in the case of 40 micron, but thick coatings showed unstable behavior where the area of flaking became very large once the film debonded off. We also made comparison between single- and multi-layered diamond coatings. Multi-layered coatings showed better durability in cutting tests. It was confirmed by a new method of measurement for the toughness of thin films, that multi-layered coatings had higher toughness than single-layered ones to deterrent crack propagation. By putting together the results above, the diamond-coated drills with optimized structure were newly developed. Their performance appeared to be satisfactory in cutting high silicon aluminum with even more than 22% silicon content.
DP-1-35 Diamond-Like Carbon Films Deposited on Polyethylene Terephthalate Substrates H. Kodama, A. Kimura, T. Suzuki (Keio University, Japan) Many studies have been reported on diamond-like carbon (DLC) films on metals and ceramics so far, but those on polymer substrates have not reported very well. In this study, we deposited DLC films on polyethylene terephthalate (PET) substrates using the rf-plasma CVD method, and analyzed morphology and chemical bonding of the films comparing with those on Si substrates. The growth rate of DLC films was larger at the initial stage of DLC deposition than at the final stage. When the deposition time was over 10 seconds, the growth rate became smaller and DLC films grew linearly as function of the deposition time. From the X-ray photoelectron spectroscopy (XPS), the peak of C1s spectra shifted to high binding energy with increase of the deposition time, which showed that the sp³ bonding increased and became stable after 10 seconds. Similar results were obtained on Si substrates. When the rf power input were high, spectra of DLC films on PET substrates shifted to high binding energy, while it was not observed for films on Si substrates. These results suggest that the chemical bonds of PET surface were changed with rf input power. To investigate the changes in chemical bonds of films and substrates, we will analyze the interface structure between DLC and PET substrates through transmission electron microscopy (TEM).
DP-1-36 Depth Resolved Comparative Investigation of Phase Formation and Stress Build-Up in Cubic Boron Nitride Films A. Klett, R. Freudenstein, W. Kulisch (University of Kassel, Germany); Y. Min, M.P. Delplancke-Ogletree (Universite Libre de Bruxelles, Belgium) Cubic boron nitride thin films have been deposited by means of ion assisted PVD and CVD techniques, namely ion beam assisted deposition (IBAD, boron evaporation and Ar/N₂ ion bombardment), and electron cyclotron resonance plasma CVD from B₂H₆, Ar and N₂. The deposition was carried out on specially designed silicon cantilever substrates which allow precise stress measurements. After deposition, the film were etched back in steps of ca. 10-15 nm by Ar ions. After each step, the stress , the thickness and also an FTIR spectrum were measured. By this means, the stress distribution, the development of the c-BN content and also the thickness of the h-BN nucleation layer and the transition layer h-BN --> c-BN could be determined. Major differences were found between the two types of layers: IBAD films possess a h-BN nucleation layer with a thickness of 15-20 nm and a stress of about 3 GPa. After c-BN nucleation, a transition region of ca. 20 nm is observed in which the c-BN content rapidly increases to the final value which can exceed 90 % . However, the c-BN toplayer possesses high compressive stresses with values up to 20 GPa. In contrast, for ECR films the transition from the h-BN nucleation layer to the c-BN toplayer is much more gradual (nucleation layer thickness ca. 50 nm). Simultaneously, the c-BN content of the toplayer is limited to ca. 70% while its stress is much lower (2-3 GPa). The reasons for these differences in phase formation and stress build-up will be discussed in terms of the differences between the two deposition techniques. Especially, the hydrogen containing gas phase used for ECR deposition seems to play a most important role.
DP-1-37 Significance of Controlling Key Process Parameters During DLC Deposition Using RF Plasma Enhanced CVD N. Ali, W. Ahmed (Manchester Metropolitan University, United Kingdom) Diamond like carbon (DLC) coatings find large usage in industry mainly due to their excellent combination of properties. In this study, thin films of DLC have been deposited on silicon substrates using capacitively coupled plasma-enhanced chemical vapour deposition (PECVD) system. The as-grown DLC films were found to be fairly thin (less then 1 micron) and amorphous in nature. RF power was found to be a critical process parameter for controlling the film properties such as microhardness, surface roughness, film morphology and coating adhesion. This was attributed to the changes taking place within the plasma such as the self-bias voltage, which became more negative with increasing RF power at low pressures. The deposition rate and the surface roughness values of the films were found to be proportional to the RF power. The films became more porous as the self-bias voltage became more negative possibly due to enhanced ion-bombardment. The coating adhesion was accessed using indentation tests combined with acoustic emission signals. Indentation tests showed that on increasing the RF input power from 100 W to 250 W, the critical load (i.e. the load at which the coating adhesion fails) changed gradually from 8N to 3N, indicating a decrease in the coating adhesion. .
DP-1-38 Effects of Noble Gases (He, Ne, Ar) on the Growth of Diamond and Diamond-Like Carbon in Hot-Filament CVD V. Baranauskas, H.J. Ceragioli, A.C. Peterlevitz (Universidade Estadual de Campinas, Brazil); S.F. Durrant (Feec, Unicamp, Brazil) In this work, we present experimental results of the CVD of diamond and diamond-like carbon from ethanol vapor and hydrogen with the partial substitution of hydrogen by noble gases. We compare the influence of the filament and substrate temperature at increasing proportions of He, Ne, or Ar in the gas feed and the influence of such gases on the kinetics of carbon deposition. The substitution of hydrogen by noble gases alters the heat transfer from the filament to the substrate due to the smaller thermal conductivity of the noble gases compared to the atomic hydrogen produced at the filament. The presence of the noble gases in the reactor chamber also minimizes the deposition of hydrogenated carbon between the grains and increases the porosity of the deposited material. Depending on the noble gas concentration, diverse structures, such as high quality diamond, porous diamond, diamond-like carbon and microwires can be deposited. A critical discussion of the results obtained in the characterization of the samples by scanning electron microscopy (SEM), photoluminescence and micro-Raman spectroscopy is presented.
DP-1-39 Substrate Bias Effect on Amorphous Diamond-Like Carbon Films Deposited by Filtered Cathodic Arc System C.-F. Chen, Y.-W. Li, Y.-B. Shue (National Chiao Tung University, Taiwan, ROC) Sputtered amorphous carbon films have been extensively used for the overcoats of magnetic thin film recording disks in the last 15 years. These films have the properties of high wear resistance, low friction characteristics and chemical inertness that are the critical requirements of a good overcoat. The typical thickness of sputtered carbon overcoats decrease gradually over the years and now stands at about 10-12 nm. The films made by the process may not meet film continuity, mechanical and corrosion requirements at the ultra-thin level ( < 10 nm). In order to sustain the phenomenal growth rate in areal density, efforts are under way to develop alternative technology. Filtered arc deposition (FAD) is an emerging technology for the deposition of amorphous hard carbon films. Furthermore, FAD focus ultra-thin amorphous hard carbon films of high sp ³ content and low coefficient of friction. These properties make it of great interest for head/disk interface application, in particular for contact recording. In the present study, we briefly describe the 45-degree angle magnetic filtered arc deposition and investigate the influence of substrate bias on hardness of a-C:H and a-C:N films. We try to correlate the microstructure, chemical composition, and chemical bonding states with hardness of the corresponding films. It found that DLC films have highest hardness with substrate bias between - 50 V to - 100 V and the hardness doesn’t seems to have good correlation with Raman I(D)/I(G) ratio. Films have higher hardness when they have higher fraction of sp ³ content. It also found that nitrogen content increase with increasing substrate bias on a-C:N films, but hydrogen content decrease with increasing substrate bias on a-C:H films. Nitrogen and hydrogen both has effect on the small graphitic crystalline growing.
DP-1-40 Ion Beam Assisted Magnetron Sputtering Deposition of Amorphous Carbon Nitride (a-CNx) Film H.S. Jung, H.H. Park (Yonsei university, Korea) Amorphous carbon films containing nitrogen (a-CN_x) have been the focus of research efforts for past years. So this increasing interest of deposition of a-CN_x requires an in-depth study on the correlation between deposition parameters and properties of film.@In this manuscript, to elucidate above relationship, the novel ion assisted deposition (IBAD) methods of a-CN_x deposition was developed and systematic characterization of deposited a-CN_x film has been proposed. IBAD in this experiment is a combination of nitrogen ion source and magnetron sputtering deposition. The nitrogen ions were produced by Kaufman ion beam source at the different ion energy range in order to study the role of nitrogen in amorphous carbon films. a-CN_x films were deposited on Si (001) substrates with the variation of nitrogen ion energy from 50 to 3000 eV. To observe the effect of nitrogen incorporation on the film properties clearly, we have carried out in-situ heating X-ray photoelectron spectroscopy (XPS) analysis for the deposited a-CN_x films. Also, the variation of bonding states, surface morphology, electrical and optical properties of a-CN_x films were characterized. Putting the results together, we established mutual relation between the effect of nitrogen ion beam and property-modification of amorphous carbon film with varying nitrogen ion energy range and substrate temperature.
DP-1-41 Deposition of Polycrystalline Diamond Coating on Cylindrical Substrates in Linear Arc Assisted Cvd Reactor V.I. Gorokhovsky (Arcomac Plasma Processing Lab, Canada) The Linear Arc Assisted CVD reactor ¹ overcomes the disadvantages of conventional Arc Torch CVD reactors by creating a homogeneous, concentrated plasma column in a cylindrical reaction tube with a length of 1 m. Substrate holders are configured to act as a reaction tube liner confining the arc in a channel containing the substrates. Approximately 1000 cylindrical substrates 2 mm dia x 20 mm long can be mounted and coated simultaneously in the reactor. Longitudinal and transverse magnetic fields are used to manipulate the plasma column into contact with the substrates. The morphology and composition of CVD diamond coatings were assessed using Micro-Raman spectroscopy and secondary electron microscopy and compared as a function of the substrate position within the reactor. Results indicate that films deposited in different parts of the reactor are very similar. A comparison of characteristics of films deposited on Mo, W, and stainless steel substrates is also presented, showing the most inconsistent films resulting when using stainless steel substrates. @¹V.Gorokhovsky, U.S.Patent No. 5,587,207
DP-1-42 Study of Carbon Containing Cubic Boron Nitride (c-BN:C) Films by Ionized PVD M.S. Wong, C.H. Lee, T.H. Tsai, T.S. Yang (National Dong Hwa University, Taiwan) Boron carbon nitride (BN:C) films were prepared by sputtering a boron carbide (B₄C) target in argon and nitrogen plasma using reactive DC magnetron sputtering technique. Various processing parameters were explored to grow BN:C films with high c-BN content. FTIR, SEM, TEM, AES, and Raman spectroscopy were used to characterize the phases, composition and surface morphology of the films. Significant influence of substrate bias voltage and temperature on phase composition of the films was found. The deposited BN:C films exhibit h-BN, w-BN, c-BN phases and their mixed phases with the variation in substrate bias and temperature. A multi-stage deposition technique with variable substrate bias was exploited to obtain unbroken films of 90% c-BN:C with thickness up to 600 nm and the films haave clear grains and facets. Multilayered films containing c-BN and other metal nitride are attempted to deposit thicker intact films.
DP-1-43 Formation of Faceted, Ballas-Like and Nanocrystalline Diamond Films Deposited in CH₄/H₂/Ar MPCVD M.S. Wong, T.S. Yang, J.Y. Lai, C.L. Cheng (National Dong Hwa University, Taiwan) The influence of Ar addition in CH₄/H₂ plasma on the crystallinity, morphology and growth rate of the diamond films deposited in MPCVD was investigated using SEM, XRD and Raman spectra. X-ray diffraction patterns indicate that diamond films of strong (111) texture are produced in these samples. With the increasing Ar concentration above 30 vol.%, (111) faceted diamond turns gradually into ballas-like diamond with graphitic inclusions, as demonstrated by SEM and Raman spectra. As the Ar concentration goes above 90 vol.%, nanocrystalline diamond films are formed, characterized by 1150 cm-1 peak in the Raman spectra and morphology observation. Diamond growth by CH₃· or by C₂ mechanism is proposed to interpretate the change in growth rate of diamond films with the variation of Ar content in the plasma.
DP-1-44 Thermal and Optical Properties of Diamond Films Deposited by the Multi-Cathode Direct Current Plasma Assisted CVD Method J-K Lee (Korea Institute of Science and Technology (KIST), South Korea); Y.-J. Baik, K.Y. Eun (Korea Institute of Science and Technology (KIST), Korea); J.W. Park (Hanyang University, Korea) With microwave-plasma CVD and DC arc-jet CVD, the multi-cathode direct current plasma assisted chemical vapour deposition (DC PACVD) is an established method for depositing thick diamond films with high quality. The multi-cathode DC PACVD using seven cathodes(7-cathode DC PACVD) allows to deposit 4-inch thick freestanding diamond wafers with thermal management grade. In this study, we report on the deposition of optical-quality diamond films by the 7-cathode DC PACVD apparatus. Diamond films have been grown on a substrate of 3 inches in diameter, as a function of the methane concentration in hydrogen gas and substrate temperatures. Other deposition parameters such as input power, operating pressure and flow rate were 17 kW, 100 Torr and 200 sccm, respectively. The variation ranges of the methane concentration in hydrogen gas and substrate temperatures were between 5% and 10% and between 1220 °C and 1300 °C (this temperatures were measured by an optical pyrometer, and expected to be more than 200 °C higher than real one owing to overlapping of the emission from hot cathodes of which the temperature was kept above 2200 °C), respectively. Optical (visible and IR ranges) and thermal properties of diamond films have been analyzed. Optical and thermal properties of diamond films were enhanced with decreasing the methane concentration and the substrate temperatures. In 5%CH₄ and 1220 °C, a diamond film with high thermal conductivity of 21 W/cmK and high optical transmittance of 70%(at 10 um) was successfully deposited at a growth rate of 4-5 um/h. These qualities should be sufficient to apply the film to optical windows such as CO₂laser window.

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